Semi-circular pulmonary vein ablation catheter

ABSTRACT

A medical device is disclosed, including a handle assembly; an elongate body coupled to the handle assembly, the elongate body defining a guide wire lumen therethrough; and a substantially semi-circular electrode array coupled to the elongate body. The device may include a substantially rigid shaft extending distally from the elongate body and defining a lumen therethrough, the shaft including a substantially rigid segment, and a flexible coil coaxial with and extending distally from the shaft.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a Divisional of and claims priority to U.S. Ser. No.13/281,761, titled SEMI-CIRCULAR PULMONARY VEIN ABLATION CATHTER, filedOct. 26, 2011, the entirety of which is incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

n/a

FIELD OF THE INVENTION

The present invention relates to medical systems and methods of usethereof having a selectively configurable treatment array.

BACKGROUND OF THE INVENTION

Numerous procedures involving catheters and other minimally invasivedevices may be performed to provide a wide variety of treatments, suchas ablation, angioplasty, dilation or the like. For example, to treatcardiac arrhythmias, physicians often employ specialized ablationcatheters to gain access into interior regions of the body. Suchcatheters include tip electrodes or other ablating elements used tocreate ablation lesions that physiologically alter the ablated tissuewithout removal thereof, and thereby disrupt and/or block electricalpathways through the targeted tissue. In the treatment of cardiacarrhythmias, a specific area of cardiac tissue having aberrantelectrically conductive pathways, such as atrial rotors, emitting orconducting erratic electrical impulses, is initially localized. A user(e.g., a physician) directs a catheter through a vein or artery into theinterior region of the heart that is to be treated. Subsequently, theablating portion of the selected device is next placed near the targetedcardiac tissue that is to be ablated, such as a pulmonary vein ostium oratrial wall.

An ablation procedure may involve creating a series of inter-connectinglesions in order to electrically isolate tissue believed to be thesource of an arrhythmia. During the course of such a procedure, aphysician may employ several different catheters having variations inthe geometry and/or dimensions of the ablative element in order toproduce the desired ablation pattern. Multiple devices having varyingdimensions and/or shapes may also be employed to account for variationsin anatomical dimensions from patient to patient. Each catheter may havea unique geometry for creating a specific lesion pattern or size, withthe multiple catheters being sequentially removed and replaced to createthe desired multiple lesions. Exchanging these various catheters duringa procedure can cause inaccuracies or movement in the placement andlocation of the distal tip with respect to the tissue to be ablated, andmay further add to the time required to perform the desired treatment.These potential inaccuracies and extended duration of the particularprocedure increase the risk to the patient undergoing treatment.

In addition, while some existing devices provide may provide for someadjustability in their geometry, the effective ability to make suchadjustments may be hampered by kinking or other unwanted impediment thatfrustrates the ability of one or more controls on a proximal portion ofa device operated by a physician to accurately translate into thedesired modification at a distal portion of a device within the patient.

In light of the above, it is desirable to provide a medical devicehaving multiple, effectively-controllable shapes or dimensions, therebyreducing or eliminating the need for additional medical devices havingvaried, but limited geometric orientations, and thus, limited ability toprovide multiple ablative patterns or sizes.

SUMMARY OF THE INVENTION

The present invention advantageously provides a medical system andmethods of use thereof providing multiple, effectively-controllableshapes or dimensions. For example, a medical device is disclosed,including a handle assembly; an elongate body coupled to the handleassembly, the elongate body defining a guide wire lumen therethrough;and a substantially semi-circular electrode array coupled to theelongate body. The electrode array may be transitionable into asubstantially linear configuration and/or may include a plurality ofelectrodes disposed on a carrier arm, the electrodes being disposed onapproximately 50% of the length of the carrier arm. At least a portionof the carrier arm may be coaxial with the guide wire lumen, and/or thecarrier arm may define an opening for passage of a guide wire. Thecarrier arm may define a rounded distal tip. The medical device mayinclude a substantially rigid shaft extending distally from the elongatebody and defining a lumen therethrough, the shaft including asubstantially rigid segment, and a flexible coil coaxial with andextending distally from the shaft. A distal end of the carrier arm maybe movably coupled to the shaft. The device may include a linearactuator coupled to the carrier arm for the linear manipulation thereofand/or a rotational actuator coupled to the carrier arm for therotational manipulation thereof. The device may include a radiofrequencysignal generator in electrical communication with the electrode array.

A medical system is also disclosed, the system including a catheter bodydefining a proximal portion and a distal portion; a substantially rigidshaft extending from the distal portion of the catheter body; a flexiblecoil extending from the shaft; a carrier arm fixedly coupled to thecatheter body and movably coupled to the shaft; and an electrode arraydisposed on the carrier arm. The electrode array may be transitionablefrom a substantially linear configuration to a substantiallysemi-circular configuration. The system may include a distal stopcoupled to the shaft that limits a range of movement of the carrier armand/or the catheter body may include a guide wire lumen coaxial with theshaft. The system may include an electrocardiograph unit in electricalcommunication with the electrode array; and a radiofrequency signalgenerator in electrical communication with the electrode array. Thesystem may include a linear actuator coupled to the shaft for the linearmanipulation thereof and/or a handle assembly coupled to the proximalportion of the catheter body.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is an illustration of an example of a medical system constructedin accordance with the principles of the present disclosure;

FIG. 2 is an illustration of an example of a medical device for use withthe system shown in FIG. 1;

FIG. 3 is an illustration of another example of a medical device for usewith the system shown in FIG. 1;

FIG. 4 is an illustration of still another example of a medical devicefor use with the system shown in FIG. 1;

FIG. 5 is a side view of the medical device shown in FIG. 4;

FIG. 6 is an illustration of another example of a medical device for usewith the system shown in FIG. 1;

FIG. 7 is an illustration of an example of a material construction of aportion of the medical device shown in FIG. 6; and

FIG. 8 is an illustration of an example of a handle assembly for amedical device.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure advantageously provides examples of medicalsystems and components thereof providing multipleeffectively-controllable shapes or dimensions that can be selectivelymanipulated to provide varying treatment patterns. In particular and asshown in FIG. 1, a medical system, generally designated as “10,” isprovided for diagnosing and/or treating unwanted tissue conditions,including atrial fibrillation or other arrhythmias. The medical systemmay generally include a radiofrequency (“RF”) signal generator 12 havinga user interface for the operation and control thereof, anelectrocardiogram (“ECG”) unit 14 operably coupled to or otherwiseinterfaced with the RF signal generator 12, and a medical device 16operably coupled to or otherwise interfaced with the RF signal generator12 and/or the ECG unit 14.

Now referring to FIGS. 1-6, the medical device 16 may include a catheterbody sized and dimensioned to intraluminally and transseptally access aleft atrium of a patient's heart for the subsequent treatment orablation thereof. The medical device 16 may generally define anelongated, flexible catheter body 18 having a distaldiagnostic/treatment assembly 20, as well as a handle assembly 22 at aproximal end or portion of the catheter body 18. The catheter body 18may define one or more lumens therethrough, to allow for the passage ofa guide wire 24 or the like therethrough. The catheter body 18 mayinclude reinforcement elements or otherwise be constructed to providedesired degrees of stiffness, flexibility, and/or torque transmissionalong the length of the body and at discrete locations along the lengththereof. For example, the catheter body 18 may include wires, braiding,increased wall-thickness, additional wall layering, sleeves, or othercomponents reinforcing or otherwise supplementing an outer wall orthickness along its length. Discrete portions that may experiencesignificant loading or torque during a particular procedure may alsoinclude such reinforcement.

Now referring to FIGS. 2-5, the distal diagnostic/treatment assembly 20provides for the treatment, monitoring, and/or otherwise clinicallyinteracting with a desired tissue region, such as the heart. Thetreatment assembly 20 may include, for example, an electrode array 28disposed near, on, or substantially on the distal end of the catheterbody. The electrode array 28 may include a plurality of electrodes 30along its length. These electrodes 30 may be symmetrically orasymmetrically mounted to detect electrical signals between any pair ofelectrodes (bi-pole) for mapping of electrical activity, and/or forperforming other functions such as pacing of the heart. Moreover, theelectrodes 30 may deliver ablation energy across an electrode pair orfrom independent electrodes when delivering monopolar energy. Eachelectrode 30 may include an integral thermocouple (not shown) located onor near the tissue side of the electrode to monitor the temperature ateach ablation site before and during ablation. The electrodes 30 may beconstructed from platinum, iridium, gold, silver or the like, and maymeasure approximately about 3 mm in length and separated by a distanceof approximately 1 mm to approximately 4 mm, for example.

Each of the electrodes may be electrically coupled to the RF signalgenerator 12, which may also be attached to a patch or ground electrode34 (attached to the back of the patient, for example) to enable thedelivery of monopolar ablation energy when desired. While monopolar andbipolar RF ablation energy may be the selected forms of energy to passthrough the electrodes of the medical device, other forms of ablationenergy may be additionally or alternatively emitted from the treatmentassembly, including electrical energy, magnetic energy, microwaveenergy, thermal energy (including heat and cryogenic energy) andcombinations thereof. Moreover, other forms of energy that may beapplied can include acoustic energy, sound energy, chemical energy,photonic energy, mechanical energy, physical energy, radiation energyand a combination thereof.

As shown in FIGS. 2-5, the treatment assembly 20 of the medical device16 may include a carrier assembly 36 that supports the electrode array28 thereon. The carrier assembly 36 may include a flexible carrier arm38 having one end coupled to the catheter body 18 and/or handle assembly22. The carrier arm 38 may be constructed from a shape memory material,such as nitinol, to provide one or more pre-determined and/or biasedgeometric configurations. The carrier assembly 36 may includereinforcement elements or otherwise be constructed to provide desireddegrees of stiffness, flexibility, and/or torque transmission along itslength or at discrete locations along the length thereof. For example,the carrier arm 38 may include wires, braiding, increasedwall-thickness, additional wall layering, sleeves, or other componentsreinforcing or otherwise supplementing an outer wall or thickness tominimize the likelihood of structural failure resulting from theexperienced torque or strain. Conventional marking elements (e.g.radiopaque markers) may be included in the distal treatment assembly 20,carrier assemblies or other components of the medical device 16 todetermine the relative location of the carrier assembly and/or thedeployment condition of the carrier assembly, as well as confirm contactwith tissue.

Referring now to FIGS. 2-3, the carrier arm 38 may extend from a distalend of the catheter body 18 in a substantially coaxial arrangement withthe catheter body 18 and/or a guide wire lumen defined therein. Thecarrier arm 38 may further define an opening or aperture 40 allowingpassage of the guide wire 24 therethrough. As a result, the guide wire24 may be used to direct the distal assembly 20 of the medical device 16into a desired position within the patient when the carrier assembly 36is in a minimized, substantially linear configuration. Further, theaperture 40 enables manipulation and steering of the guide wire 24independently of the carrier assembly 36, allowing the distal portion ofthe medical device 16 to be directed over-the-wire irrespective of thegeometric shape or configuration the carrier assembly is in, or what theparticular rotational position of the carrier assembly is with respectto the guide wire 24. For example, FIG. 2 illustrates the carrierassembly 36 in a first geometric configuration for diagnosing ortreating a tissue area, while FIG. 3 illustrates an additional geometricconfiguration.

Now turning to FIGS. 4-5, the carrier assembly 36 may extend from adistal end of the catheter body 18 offset or spaced from an opening inthe distal end where the guide wire 24 exits the catheter body 18. Thisconfiguration again allows for independent and separate operation ormanipulation of the carrier assembly 36 and the guide wire 24 when thedistal assembly 20 is in the treatment area, which may include forexample one or more chambers of the heart.

The electrode array 28 may be arranged in a resiliently biased mannerand have specific geometric configurations which generally allow theelectrodes 30 to ablate specific tissue (such as a pulmonary vein, forexample) having predetermined or otherwise known geometric ortopographical characteristics. The electrode array 28 may be selectivelymovable from a primary, stored or delivery configuration for transportand delivery to the treatment site (such as a radially constrainedconfiguration) to multiple secondary, deployed or expandedconfigurations for treatment. Referring now to FIGS. 2-5, the electrodes30 may be spaced along a fraction of the length of the carrier arm 38(for example, between approximately 40% to approximately 60% of theoverall length) such that, when deployed into an expanded configuration,the electrodes constitute a substantially semi-circular array. Thefractional length and substantially semi-circular configuration of theelectrodes allows a user to provide therapy with the electrodes aroundlarger/common ostia or vessel orifices, as well as providing increasedability to create larger, wider-area patterns of treatment on moreantral surfaces or tissue regions.

Referring now to FIGS. 6-7, the medical device 16 may include a shaft 42extending distally from the catheter body 18. The shaft 42 may besubstantially rigid (e.g, constructed of stainless steel or the like)and define a lumen therein for the passage of the guide wire 24. Aflexible coil 44 may be coupled to the shaft 42, and the coil 44 may bedeflectable or steerable from the handle 22 of the device 16, and/or thecoil 44 may define a lumen therethrough for passage of the guide wire 24to facilitate over-the-wire direction of the medical device 16. Anintermediate conduit 46 may be disposed between the shaft 42 and thecoil 44, where the intermediate conduit provides a degree of rigidityless than the shaft 42 but greater than the coil 44, thus providing atransitional area that can deflect or bend to a degree during deflectionor steering of the medical device 16. The intermediate conduit may beconstructed, for example of nitinol or other material having the desireddegree of flexibility.

The carrier arm 38 and/or carrier assembly 36 may be movably coupled tothe shaft 42, and the shaft may be movable with respect the catheterbody 18 to aid in shaping or manipulating the carrier assembly 36 into adesired configuration. The carrier arm 38 may define an eyelet oropening slidably positionable along a length of the shaft 42, forexample. A distal stop 48 may be coupled to the shaft 42 to limit arange of movement of the carrier assembly 36 and/or preventunintentional retraction/de-coupling of the shaft 42 and the carrierassembly 26. The stop 48 may include an expanded diameter portion orother mechanical obstacle preventing movement of the carrier assembly 36past a certain point.

The handle assembly 22 of the medical device may include one or moremechanisms or components to facilitate manipulation of the shaft and/orthe distal treatment assembly. For example, as shown in FIG. 8, thehandle assembly 22 may include a linear actuator 50 providing for theproximal-distal extension and retraction of the shaft 42 and/or carrierassembly 36. The linear actuator 50 may be movably coupled to a portionof the handle assembly 22 to allow it to slide or otherwise translate ina proximal-to-distal direction, and vice versa. The handle assembly 22may further include a housing coupled to the linear actuator 50 and/orhandle assembly 22 to facilitate movement and/or linkage of the actuatorand the shaft 42 and/or carrier assembly 36.

A rotational actuator 52 may also be disposed on or about the handleassembly 22 to facilitate rotation of the shaft 42 and/or carrierassembly 36 about a longitudinal axis of the catheter body 18 in twodirections. The rotational actuator 52 may be directly coupled to theshaft, or alternatively, include one or more intermediary components toeffectuate a controllable, mechanical linkage between the rotationalactuator and the shaft 42 and/or carrier assembly 36, such as asecondary gear assembly.

One or more internal push/pull wires may also be provided in the medicaldevice 16, and in particular, coupled to the handle assembly 22. Forexample, to facilitate single or bi-directional steering and control ofthe distal treatment assembly 20, a full length pull wire (or doublepull wires such as in the case with bi-directional steering, neither ofwhich is shown) may be secured to the a distal portion of the end of theshaft 42 and/or carrier assembly 36. The pull wire may extend proximallyto a steering knob 54. Rotation of the knob 54 may pull the wire that,in turn, controls the plane in which the electrodes contact tissue.

The medical device may further include a capture element 56 that isfriction fit over a distal end of the handle assembly 22. The captureelement 56 may be configured to be detached therefrom and slide in adistal direction over the catheter body 18 until the electrode array 28is received therein, in a stored or confined configuration. The captureelement 56 may be applied over the electrode array 28 for constraint andprotection thereof during delivery through a hemostasis valve of atransseptal sheath or a vascular introducer. In this manner, the arraymay be introduced safely (e.g. without damage) into the patient'svasculature (e.g., a femoral vein). After introduction of electrodearray 28 through the hemostasis valve, the capture element 56 may bemoved proximally over the catheter body and reattached to the distal endportion of the handle assembly 22 to function as a strain relief.

The RF signal generator 12 functions to generate RF energy as suppliedto selected catheter electrodes or between selected pairs of electrodesfor the electrode array 28 to ablate or otherwise treat cardiac tissue.In particular, the RF signal generator 12 may be configured to generateand control the delivery of RF energy based on temperature feedback fromthe respective thermocouple of each electrode 30. Each electrode 30 maybe independently monitored followed by temperature-controlled deliveryof RF energy. Energy delivery may further automatically be duty-cycledto maximize the delivery of RF energy to the electrode based on themeasured tissue temperature. Hence, as the tissue temperature increasesdue to delivery of RF energy (resistive heating), the electrodes 30 inturn increase in temperature, as monitored by the correspondingthermocouple. For instance, during bipolar delivery, if the set targettemperature of the electrodes is 60° C. and one of the two electrodes ismonitored at 55° C., while the other electrode is monitored to be at 50°C., the generator will selectively limit energy delivery based on theneeds of one electrode measured at 55° C. This prevents either electrodeof the pair from ever significantly surpassing the set targettemperature. In contrast, during a monopolar phase of the energydelivery, the RF signal generator will deliver RF energy to eachelectrode 30 solely based on the temperature measured by itscorresponding thermocouple. The temperature measurements may beperformed between RF duty cycles (off-cycles) to minimize interferenceand to optimize accuracy of temperature readings.

The RF signal generator 12 may also include a user interface 56 and/or aremote control 58 (shown in FIG. 1). The user interface 56 allows a userto select parameters for the desired mapping and/or ablation treatment.The user interface 56 may allow the user to select an energy deliverymode for the treatment. For example, the user interface 56 can allow theuser to select the delivery of only monopolar energy, only bipolarenergy, or a combination of the two. The user interface may also allowthe user to select a power ratio, such as 1:1, 2:1, or 4:1, when incombination mode. The generator 12 can be manufactured to includespecific alternative power ratios (e.g., 1:1, 2:1, 4:1), such that theuser can select one of the established ratios, and/or the user interfacecan allow the user to enter a different power ratio. The user interface56 may also allow the user to change the energy mode when the catheteris changed, or when the medical device is moved to a different locationin order to ablate different tissue.

The ECG unit 14 is provided to monitor and map signals detected by theelectrodes of each electrode array. These two units (i.e., the RF signalgenerator 12 the ECG unit 14) may be interfaced in parallel, via the ECGinterface 14, to the medical device 16. The ECG unit 14 electricallyisolates the ECG unit 14 from any damaging signals generated by the RFgenerator 12. The ECG unit 14 may also be configured to isolate the ECGmonitoring unit from electrical noise generated by the delivery of theRF energy.

In an exemplary use of the present system, the medical device 16 may beused to investigate and treat aberrant electrical impulses or signals ina selected tissue region, such as in the heart. Primarily, the distaltreatment assembly 20 may be advanced through the patient's vasculaturevia the femoral vein over a previously inserted guide wire 24. Thedistal treatment assembly 20 may then be advanced into the right atriumand into proximity of a pulmonary vein, for example. In order to advancethe carrier assembly 36 through the vasculature and into the desiredposition, the distal treatment assembly 20 (including the carrierassembly 36 and the electrode array 28) may be oriented in a first,substantially linear transport configuration. The first, substantiallylinear transport configuration may be achieved through the manipulationof the linear actuator 50 on the handle assembly 22. In turn, theflexible carrier arm 38 may be urged toward the substantially linearconfiguration. In this linear orientation, the carrier assembly isminimized and compact in a transverse dimension for easily advancedthrough the vasculature (or a transseptal sheath).

Once in the desired proximity to the target tissue, the carrier assembly36 and the electrode array 28 may be deployed into a second, expandedgeometric configuration using one or more of the rotational actuator 52and/or linear actuator 50. Upon obtaining the desired geometricconfiguration of the carrier assembly and electrode array, the steeringmechanism of the medical device (e.g., the steering knob 54 and theinternal pull wire or wires) may be used to deflect the array 28 tocontact the target tissue. The deflection may be achieved independentlyof the placement or manipulation of the guide wire 24. At this juncture,the geometric configuration of the electrode array 28 can be furtheradjusted to achieve optimal contact with the surrounding targetedtissue. Further, once a desired configuration of the carrier assembly 36has been achieved, the configuration may be maintained when moving fromone position or tissue treatment area to another region or tissuetreatment area using the guide wire 24. Such methodology would allow auser, for example, to configure the carrier assembly 36 and electrodearray 28 into the desired size or shape for a first pulmonary vein (orother tissue structure), then move the array 28 over the guide wire 24to a similar structure (e.g., a second pulmonary vein) without the needto modify the shape of the array.

Once in the desired position, sufficient contact with tissue may bedetermined when the carrier assembly transitions to a convex shape orthrough fluoroscopic imaging. In addition, the location and tissuecontact can be confirmed using the electrodes 30 of the medical device.For example, an electrophysiologist can map the contacted tissue to notonly determine whether or not to ablate any tissue, but to also confirmtissue contact which is identified in the mapping procedure. Ifconditions are determined to be inadequate, an operator may adjust theshape or deflection of carrier assembly and/or the operator mayreposition carrier assembly 36 against tissue through variousmanipulations performed at the proximal end of medical device 16.Moreover, it will be appreciated that other conventional mappingcatheters can be applied to map signals, such as a standardelectrophysiology lasso catheter.

Once sufficient tissue contact has been established and the mappingprocedure has confirmed the presence of aberrant conductive pathways,ablation energy may be passed through the electrodes 30 (i.e., 5-10Watts) of the electrode array 28. The electrode array 28 and the RFsignal generator 12 may cooperate to deliver RF energy in monopolar,bipolar or combination monopolar-bipolar energy delivery modes,simultaneously or sequentially, and with or without durations ofterminated energy delivery.

Depending upon a number of primary factors, such as the geometry andlocation of targeted tissue region, the quality of the electrode/tissuecontact, the selected magnitude of the RF energy delivered to theelectrodes, the type of RF energy applied, as well as the duration ofthe ablation, lesion formation can be estimated that is sufficient toeliminate aberrant conductive pathways therethrough. For example, giventhe above factors, a target temperature of the ablated tissue may beabout 60° C., with a lower limit of about 55° C. and an upper limit ofabout 65° C.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention, which is limited only by the following claims.

What is claimed is:
 1. A medical system, comprising: a catheter bodydefining a proximal portion and a distal portion; a substantially rigidshaft extending from the distal portion of the catheter body; a flexiblecoil extending from the substantially rigid shaft; a carrier arm fixedlycoupled to the catheter body and movably coupled to the substantiallyrigid shaft; a distal stop coupled to the substantially rigid shaft thatlimits a range of movement of the carrier arm; and an electrode arraydisposed on the carrier arm.
 2. The medical system of claim 1, whereinthe electrode array is transitionable from a substantially linearconfiguration to a substantially semi-circular configuration.
 3. Themedical system of claim 1, wherein the catheter body includes a guidewire lumen coaxial with the substantially rigid shaft.
 4. The medicalsystem of claim 3, wherein at least a portion of the carrier arm iscoaxial with the guide wire lumen.
 5. The medical system of claim 4,wherein the carrier arm defines an opening for passage of a guide wire.6. The medical system of claim 1, wherein the substantially rigid shaftdefines a lumen therethrough and includes a substantially rigidintermediate conduit disposed between the substantially rigid shaft andthe flexible coil.
 7. The medical system of claim 1, further comprising:an electrocardiograph unit in electrical communication with theelectrode array; and a radiofrequency signal generator in electricalcommunication with the electrode array.
 8. The medical system of claim1, further comprising a linear actuator coupled to the substantiallyrigid shaft for the linear manipulation thereof.
 9. The medical systemof claim 1, further comprising a handle assembly coupled to the proximalportion of the catheter body.
 10. A medical system, comprising: amedical device including: a catheter body having a proximal portion, adistal portion, and a longitudinal axis, and a guide wire lumen; asubstantially rigid shaft extending from the distal portion of thecatheter body; a flexible coil extending from the substantially rigidshaft; a carrier arm fixedly coupled to the catheter body and movablycoupled to the shaft; and an electrode array disposed on the carrierarm, the electrode array having a plurality of electrodes, the carrierarm being transitionable between a substantially linear configurationand an expanded configuration, the carrier arm being would in asubstantially semi-circular configuration around the longitudinal axisof the catheter body when the carrier arm is in the expandedconfiguration, all of the plurality of electrodes in the expandedconfiguration being coplanar in a plane that is substantially orthogonalto the longitudinal axis of the catheter body.
 11. The medical system ofclaim 10, further comprising a distal stop coupled to the substantiallyrigid shaft that limits a range of movement of the carrier arm.
 12. Themedical system of claim 10, wherein at least a portion of the carrierarm is coaxial with the guide wire lumen.
 13. The medical system ofclaim 12, wherein the carrier arm defines an opening for passage of aguide wire lumen.
 14. The medical system of claim 13, wherein theopening is immediately distal to the portion of the carrier arm that iscoaxial with the guide wire lumen.
 15. The medical system of claim 10,wherein the substantially rigid shaft defines a lumen therethrough andincludes a substantially rigid intermediate conduit disposed between thesubstantially rigid shaft and the flexible coil.
 16. The medical systemof claim 10, further comprising: an electrocardiograph unit inelectrical communication with the electrode array; and a radiofrequencysignal generator in electrical communication with the electrode array.17. The medical system of claim 10, further comprising a linear actuatorand a rotational actuator, each of the linear actuator and therotational actuator being coupled to the carrier arm for manipulationthereof.
 18. The medical system of claim 17, further comprising a handleassembly coupled to the proximal portion of the catheter body, thehandle assembly being in communication with the linear actuator and therotational actuator.
 19. The medical system of claim 18, wherein thehandle assembly includes a capture element over a distal end of thehandle assembly.